The United States gave a major boost to covert operations against Iran with Congress’s approval last year of President George W. Bush’s request for 400 million dollars, a US magazine reported Sunday.

The move reveals a “major escalation” in clandestine operations aimed at destabilizing the Islamic republic’s religious leadership amid concerns over Tehran’s nuclear ambitions, said the report in the New Yorker magazine citing former military, intelligence, and congressional sources.

Among the methods being used are increased US support for minority and dissident groups and intelligence gathering about Iran’s nuclear facilities, said the article, written and reported by Seymour Hersh.

Although such covert activities in Iran are not new on the part of the United States, the magazine said the “scale and the scope of the operations in Iran, which involve the Central Intelligence Agency and the Joint Special Operations Command (JSOC), have now been significantly expanded.”

The Congress approved Bush’s request for funding late last year, according to sources with knowledge of the top secret Presidential Finding, which by law must be issued when covert intelligence operations get underway.

The Presidential Finding is conveyed to a select group of Congressional leaders and their intelligence committees, otherwise known as the Gang of Eight, the report said.